Transducer indexing system for playing back various geophysical recordings



5 Sheets-Sheet l INVENTORS John R Wands Tam Pr/clraff Jn Will/0111M.Mullings James K. Lyons M 5? M A 7'7'0R/VE Y J. P. WOODS ETAL TRANSDUCERINDEXING SYSTEM FOR PLAYING BACK VARIOUS GEOPHYSICAL RECORDINGS Feb. 7,1967 Original Filed March 31 6Q mm l 3 W xmm m i 2 Amm v rfi l E56 E@885. is :85 2E LN SE28 .m 4 n m g m 55:5 ,mm M M i m unuu Q II: 7 R 55%@2582;

ATTEST.

Feb. 7, 1967 J. P. WOODS ETAL TRANSDUCER INDEXING SYSTEM FOR PLAYINGBACK VARIOUS GEOPHYS I CAL RECORDINGS Original Filed March 31, 1961 R Fa (\1 ii ATTEST 5 Sheets-Sheet 2 INVENTORS ATTORNEY Feb. 7, 1967 J. P.wooms ETAL 3,303,513

TRANSDUCER INDEXING SYSTEM FOR PLAYING BACK VARIOUS GEOPHYS I CALRECORDINGS Original Filed March 31.

3 Sheets-Sheet 3 INVENTORS. Woods BY W. M. Mull/figs J. K. gyms I ATTESTATTORNEY United States Patent C) 3 303 513 TRANSDUCER INDEXlNG SYSTEMFOR PLAYING BACK VARIOUS GEOPHYSICAL RECORDINGS John P. Woods, Dallas,Tom Prickett, Jn, Richardson,

William M. Mailings, Garland, and James K. Lyons,

Dallas, Tex., assignors to The Atlantic Refining Company, Philadelphia,Pa., a corporation of Pennsylvania Application Nov. 17, 1964, Ser. No.417,531, now Patent No. 3,268,910, dated Aug. 23, 1966, which is adivision of Ser. No. 348,322, Feb. 25, 1964, now Patent No.

3,210,770, dated Oct. 5, 1965, which in turn is a continuation of Ser.No. 99,858, Mar. 31, 1961. Divided and this application Oct. 23, 1965,Ser. No. 507,987

4 Claims. (Cl. 346139) The present case is a divisional application ofapplication Serial No. 417,531, now US. Patent 3,268,910 (filed November17, 1964) which application is in turn a division of application SerialNo, 348,322, now US. Patent 3,210,770 (filed February 25, 1964), whichin turn is a continuation of Serial No. 99,858, filed March 31, 1961,and now abandoned.

This invention relates to a playback system suitable for use with afield or ofiice type geophysical recorder or computer. Morespecifically, the invention relates to an improved transducer indexingsystem designed to reproduce seismic records in accordance withrequirements peculiar to hydrocarbon exploration and interpretation.

Magnetic recording has been known and utilized for many years; and sinceWorld War II, the use of magnetic recording in geophysical explorationhas increased at an impressive rate. However, in spite of the rapidincrease in the use of magnetic recording in this field, to date nosatisfactory recorder-playback combination capable of meeting thepeculiar requirements of hydrocarbon exploration has been invented. Inthe seismic field of geophysical exploration numerous devices are usedin an attempt to furnish a field recorder operator with a high speed,economical, and satisfactory visual check or monitoring apparatus fordetermining the success of the magnetic recorder in capturing seismicreflections in readable form. With a proper monitoring apparatus theoperator can quickly determine after each firing if the recordings aresatisfactory. If one or more of the channels are not recorded in areadable'form, a second shot or series ofshots can be fired before theparty moves on to its next location. By using the proper monitoringmeans, the party is able to save thousands of dollars in time,explosives, etc. that would normally be required in reshooting positionsat later dates. Various display or monitoring systems are used today inconjunction with magnetic recorders to check the readability of recordedsignals. Photo-graphic oscillographs, fluorescent screens, and varioustypes of recording pen systems are common devices for providing a visualcheck of magnetic recording. Probably, one of the most satisfactoryanswers to the basic monitoring requirement is found in United StatesPatent No. 2,803,515. This patent discloses a magnetic field recorderand playback combination that simultaneously records a number of seismicsignals and thereafter, for monitoring purposes, sequentially, channelby channel, transcribes the recorded seismic signals on Teledeltospaper. The device may be made to repeat the reproduction of any channelby actuating a repeat switch or may be made to return to the startposition by actuating a manual reset button. Although the'patentprovides a satisfactory basic field recording and playback combination,it is not versatile enough to meet the overall requirements ofhydrocarbon exploration. Since this type of exploration is highlyspecialized and complex, the modified conventional type playback ortranscribing system as discussed above is not satisfactory. Due to thepeculiar requirements of this specialized type of exploration, adesirable playback apparatus, in addition to af- 3,303,513 Patented Feb.7, 1967 fording a visual monitoring means, must also provide some typeof control means designed to present the transcribed information in amanner suitable for the particular purpose for which the information isto be used. Ideally, this apparatus should also be versatile enough tobe used with either a field recorder where the transcribing drum isapproximately 8 to 12 inches in length or with a central office computerwhere the drum is from 4 to 5 feet in length. This extreme variation indrum length imposes severe requirements of flexibility on the penindexing portion of the playback combination.

First, with reference to the control means requirements mentioned above,it is highly desirable in all hydrocarbon exploration and interpretationoperations, and mandatory in some, that the apparatus be versatileenough to (1) be able to select the recorded channels to be transcribed,(2) be able to adjust the width of the transcribed channels, (3) be ableto adjust the distance between the edge of the transcribing medium andthe first transcribed channel, (4) be able to provide a center gap or anarea on the transcribing medium for noting seismic information andcomputations, (5) be able to adjust the center gap as to 'width andlocation, and (6) be able to start and stop the transcribing apparatusat any desired location. The above versatility i utilized, all or inpart, either in the field to aid the monitoring operations or in aninstallation to aid record interpretation operations. The operator inthe field, in addition to utilizing the monitoring and control means tocheck recording quality, uses it to determine the type and quality offiltering required to overcome noise and interference inherent in thearea being surveyed. The magnetic channels that he desires to monitor orthe number of geophones used in the particular survey will, in mostcases, dictate the recorded channels to be transcribed, the width of theedge gap, the width and location of the transcribed channels and thewidth and location of the center gap. The use of such a versatileplayback system is even more essential when the magnetic recordings areutilized in a computer installation. Here, the playback system is usedfor such operations as transcribing new records received from the field,refiltering the new records, transcribing and refiltering forcomparative purposes old records taken in the same area or similarareas, transcribing new or old logs made in the same area, andpresenting desired combinations of the above information on the sameplayback medium for correlation purposes. In accordance with the studiesto be made, the different records to be used, and the number of channelsto be transcribed, the width of the edge gap, the width of thetranscribed channel, and the location and width of the center gap aredetermined. In addition to the above types of presentation, the playbacksystem must also be able to change previously recorded exploration datainto cross sections of the areas previously explored. I

In summary, it is obvious that a playback system satisfactory forhydrocarbon exploration and interpretation purposes cannot be onelimited to transcribing seismic data in a stereotype form. This isespecially true since it is frequently desirable to transcribe seismicinformation, appropriately recorded well logging information, as well asother types of exploration information, on the same medium so thatvisual or automatic correlations between the different information canbe made. Therefore, a satisfactory playback system must be versatileenough (1) to accommodate itself to operate on various types of recordedinformation and (2) to transcribing the information in the form thatwill facilitate interpretating the particular information transcribed.

It is, therefore, an object of this invention to provide a versatileautomatic playback system usable with either a field recorder or officecomputer and incorporating conbeing utilized either in the field or inan office.

Another object of the invention is to provide a simplified playbacksystem exhibiting a minimum of moving parts and adapted to provide fastaccurate records and dependable service under field conditions.

Another object of the invention is to provide a read and/ or writeelement indexing system capable of operating across a computer drum or afield recorder drum.

Another object of the invention is to provide a read and/ or writeelement indexing system that'is simple and dependable in operation witha minimum of moving parts. 1

Another object of the invention is to provide a read and/or writeelement indexing, clutch-brake assembly adapted to prevent servo-hunt,jitter, backlash, etc., and capable of accurate operation over a longdrum or wide chart.

Another object of the invention is to provide a simplified read and/ orwrite element indexing system with a faster response time and moreaccurate positioning system than heretofore available.

In the drawings:

FIGURE 1 is a simplified diagram of a playback system.

FIGURE 2 is an isometric drawing of a band-pulley read and/ or writeelement indexing device.

FIGURE 3 isa side view of a magnetic clutch-brake assembly used inFIGURES 2 and 4.

FIGURE 4 is an isometric drawing, partially in section, of a linearmotion solenoid read and/or write element indexing device.

, Briefly stated, the preferred form of the invention is concerned withan automatic playback system which utilizes a novel incremental motiontype indexing device adapted to operate with a monitor transcriber for amagnetic field recorder or with a transcriber for a large, office typecomputing device. The novel indexing-device is designed for minimumphysical wear and simplicity of operation so that it can function in thefield or in the oflice with a minimum of maintenance.

Within the broad statements of the invention as given above, there arenumerous combinations and subcom-binations'of apparatus which are inthemselves novel and which will be so recognize-d.

FIGURE 1 is a schematic diagram of one possible combination ofapplicants invention and conventional recording and transcribingdevices. Applicants invention is shown as pen indexing system 5associated with playback switching system 1, playback switching controlcircuit 3, magnetic recording drum 7, magnetic heads 9, detector system11, transcribing pen 13, pen amplifier 15, and transcribing drum 17.

A further and more detailed description of this embodiment follows.

The basic function of switching system 1 is to automatically andselectively connect read and write means so that previously recordeddata are automatically trans'cribedas directed by instructions set inassociated control means 3. The basic function of control means 3 is tocommand indexing system 5 to position transcribing element 13 so that itreproduces. the data in a preselected manner compatible withrequirements peculiar to hydrocarbon exploration and interpretationactivities. Control means 3 may physically be a part of. or separatefrom switching system 1.

Playback switching matrix 1, FIGURE 1, is shown as a number of gangedsequential multicontact switches 19,

21, 23 and 25. Multicontact switch 19 connects magnetic heads 9 todetector system 11. Multicontact switch 21 connects an output ofdetector 11 to the input of pen amplifier 15. Multicontact switch 23connects a voltage source 27 through a resist-or system 29 and controlcircuit 3 to the input of pen indexing means 5. The pen index mayinclude a servo mechanism, a motor drive mechanism, or a simple circuitconnected to the device depending upon the type of pen index used.Switch 25 is connected to ramp switch 3 1 on magnetic recording drum 7and is designed to be pulsed by each revolution of the drum. Each timeswitch 25 is pulsed by switch 31, the next succeeding contact on theswitch is closed, thus moving 25 and its ganged switches 19, 21 and 23to their next succeeding contacts. Switch 25 contains receptacles 33 forstart patch plug 35, center gap plug 37 and stop plug 39. As will beexplained in detail hereinafter, the proper connection of plugs andreceptacles bridges the undesired switch contacts and locates thedesired center gap on transcribe drum 17.

Control circuit 3 converts preset transcribing instructions into propercommand voltages for the pen index system. As will be detailedhereinafter, the type of pen index used determines the type of controlcircuit required. If 'a pulse type indexing de'v'ice, FIGURE 4 or 5, isused, the control system can be a simple circuit connecting a pulsecircuit, such as switch 23, FIGURE 1, to the pen index. Of course,necessary relays and patch cords connections or the like are required,as described hereinafter, to avoid the undesired channels.

Operation of the playback switching matrix and control circuit in FIGURE1 is as follows. Prior to the playback, the desired transcribeinstructions are set in the control circuit. Start plug 35, center gapplug 37, and stop plug 39 are placed in the appropriate receptacles 33.The plug positions determine the magnetic channels to be replayed andthe position of the center gap, as will be described in more detail inthe matrix subheadings. Any or all of the above instructions may bevaried after each transcribing operation or may be retained as long asappropriate.

After the desired adjustments have been made on the control circuit andpatch board, the system is then ready for a fire-record-transcribesequence or a transcribe sequence, depending on the purpose of theplayback and the type recorder being used. Assuming that the desiredinformation is already recorded on drum 7, the playback sequence is asfollows. The proper magnetic head 9 is selected by the position ofswitch 19 which in turn is determined by switch 25and the receptacle 33in which start plug 35 is inserted. The magnetically recordedintelligence under the selected head is read out and sent throughdetector systems 11, switch 21, play= back amplifier 15 to playback pen13, where it is tran= scribed on a medium mounted on drum 17. Duringthis operation, switch 23, which was simultaneously posi tioned alongwith 19 and 21, connects DC. voltage 27 to control circuit 3 where acommandsvoltage is developed. T his command voltage causes pen index 5to position playback pen 13 over an appropriate transcribe channel ondrum 17. As playback pen 13 completes the transcription of the selectedmagnetic channel, drum 7 completes a single revolution causing pen shiftramp switch 31 to close producing a DC. pulse. The DC. pulse causesswitch 25 to move to its next succeeding contact. If the succeedingcontact is bridged by center gap plug 29, the next selected contact isactivated. Since switch 25 is ganged to 19, 21 and 23, the appropriatecontact on each switch is activated and the recorded information fromthe next selected magnetic head is transcribed on drum 17. Thisoperation is repeated until the contact on switch 25, selected by stopplug 39, is energized. At that time, the DC. pulse from the, recordingdrum is short-circuited to ground, all switch contacts are cleared, andthe playback sequence is complete.

The pen indexing device 5, FIGURE 1, is designed to position playbackpen 13 over the appropriate transcribe channel on drum 17, as directedby the playback switching matrix 1 and control circuit 3. The type ofcontrol circuit used depends on the type of indexing device utilized. Ifit is desirable to use a servo-driven indexing device, a control circuitis used to develop a command voltage to operate the pen index. As willbe detailed hereinafter, the command voltage can be used to operate theservo in novel incremental steps or the command voltage can be comparedwith a second voltage to produce an error signal to operate aconventional servo indexing system. If the pen indexing mechanism is notservo-driven, the control circuit is modified accordingly. The novel penindexing mechanisms to be described hereinafter are not limited in theiroperation and can be used on a field recorder or an oflice computer withequal accuracy. In addition, they are well suited for automatic,semiautomatic or manual operation, with or without a switching matrix.Although the index mechanisms are illustrated and described as penindexing devices, it should be understood that if desired they can beused to position any type of read and/or write transducer or transducersto include magnetic heads, electric pens, ink pens, optical readoutsystems, etc.

Heretofore, most pen indexing systems have used servooperated leadscrews to position a read or write element over a desired portion of adrum or chart. The servo was operated by a conventional error voltageand rotated the lead screw until the error voltage was zero. It is wellknown that when such a servo mechanism is required to operate over aconsiderable linear distance the system loses much of its accuracy. Infact, when a conventional servo indexing device is used to move a penhousing over a distance greater than 12 inches, the problem ofinaccurately located playback channels, etc., be comes serious.Applicants novel invention has solved this problem by developing penindexing devices capable of operating over distances much greater than12 inches and still retaining a high degree of accuracy in locating theplayback channels. Applicants pen indexing devices, when operating overlong drums, utilize an incremental stepping system which retains thehigh degree of accuracy inherent in a servo system operating over a fewinches, and yet reduces the response time of such a system by a factorof two or three, depending on the particular species used. This featurewill be explained in detail hereinafter. In addition to maintainingaccuracy and reducing response time, applicants devices overcome theproblems of jitter, backlash, and servohunt by the use of a novel brakeand clutch arrangement.

Band-pulley pen indexing mechanism FIGURE 2 shows an isometric drawingof a servooperated band-pulley pen indexing device that can operate overshort or long distances with great accuracy and speed. Servo-hunt andjitter are prevented by a unique brake-clutch arrangement shown inFIGURE 3. In addition to its operational versatility, the device issimple in operation, construction, and maintenance. The band-pulleymechanism retains its high degree of accuracy by using a limitingpotentiometer and a servo drive to produce incremental linear motion.

The band-pulley indexing system shown in FIGURE 2 includes frame 203which is joined by tubular ways 205 and 207. Pen housing 209 is slidablymounted on the tubular ways. A stationary metallic band 211 is connectedbetween anchor support 213, rigidly attached to way 205 and to gearhousing 215. A rotating metallic band 217 is mounted on driving pulley219 and driven pulley 221 so that the lower portion of the band passesthrough the center of tubular way 205. The two ends of band 217 arejoined by spring 223. Band 217 passes 6 through magnetic clutch 225 andband 211 passes through magnetic brake 227. The magnetic clutch brakeassembly is described in detail under its appropriate subheading;however, for purpose of illustrating FIGURE 5, it is necessary to make abrief reference to the assembly as shown in FIGURE 3. Magnetic clutch225 includes solenoid 229 with center core 231 mounted underspringloaded rocker arm 233. When no current is applied to solenoid 229,rocker arm 233 rests against stop 235. Band 217, FIGURE 2, is positionedbetween rocker arm 233 and core 231, FIGURE 3. Magnetic brake 227,FIGURE 3, includes solenoid 237 with center core 239, spring-loadedrocker arm 241 and stop 243. Band 211, FIGURE 2, is positioned betwenrocker arm 241 and core 239, FIGURE 3. If desired, microswitch 245,FIGURE 3, can be connected to the electrical inputs 247 on clutch 225and 249 on brake 227. When 245 is depressed, actuating current isinterrupted and both rocker arms return or remain in the open positionso that the pen housing can be manually moved along the ways 205 and207, FIGURE 2.

In operation, servo 251 receives a command signal voltage from controlcircuit 3 shown in FIGURE 1. Simultaneously with the application of thecommand voltage, a voltage is applied to the inputs of the clutch andbrake assembly. This voltage activates solenoid 229, rocker arm 233 todrive band 217, and de-activates solenoid 237 so that band 211 is freeto move under rocker arm 241. Servo 251 translates the command voltageto rotary motion in a conventional manner and transmits this motionthrough its gear train 253 to puiley 219 which in turn imparts linearmotion to band 217. Since clutch 225 is now activated and rocker arm233, FIGURE 3, is secured to the band 217, FIGURE 2, pen housing 209 ismoved along ways 205 and 207 as pulley 219 rotates and moves band 217 inthe desired direction. The linear movement imparted to the pen housingis determined by the command voltage applied to the servo. After the penhousing has been indexed to the next appropriate playback channel, theactivating voltage from the playback control relay is discontinued andthe clutch is de-activated releasing band 217. If desired, anappropriate signal can be applied to brake 227 so that it is activatedbetween command voltages, however, this is an optional feature. Aftertranscribing pen 13 has recorded the appropriate information, aswitching matrix, such as shown in FIG- URE 1 causes the command circuitto send the next command voltage to the servo. The pen housing is movedover the next transcribing channel in the same manner as describedabove.

Aspointed out heretofore, the mechanisms incremental movement isdeveloped by turn limit potentiometer 255. The maximum amount of linearmotion that can be applied to the pen housing without a reset cycle isdetermined by the turn limit potentiometer. Various types of limitingpotentiometers may be used, however, a three or ten turn limit is mostdesirable with this device. In most cases, it is desirable to untilize alimit potentiometer that allows an incremental motion greater than thetotal width of the magnetic record to be played out. After this maximumlinear distance has been traversed by the pen housing, the potentiometermust experience a reset cycle before the housing can continue its linearmotion across the drum. The reset cycle in this case comes from therelay receptacle 33, FIGURE 1, in which the stop plug has been inserted.During the reset cycle, magnetic clutch 225, FIGURE 2, is de-activatedand brake 227 is activated so that when the servo rewinds the turn limitpotentiometer the pen housing remains in its present po- SIOI'I.

The term band as used herein is meant to include bands, belts and chainswhether composed of metal or otherwise. Also, it should be understoodthat other motion transmitting means can be substituted for thebandpulley means without changing the scope of the invention.

For instance, a lead screw or a Saginaw ball-bearing drive screw or evena push bar could be usedfor the motion imparting means. It a drive screwis substituted for the band-pulley means, modifications would benecessary A clutch positioned between the servo drive and the drivescrew could be substituted for the magnetic clutch-brake assembly. Thesubstituted clutch could be operated by a limit switch actuated by aturn limit potentiometer connected to the screw. With this adaptation,the servo would drive the lead screw imparting linear motion to the penhousing attached to the screw. After the pen housing traversed theincremental distance prescribed by the turn limit potentiometer, thelimit switch is activated, in turn engaging the Clutch so that the screwdrive is disengaged during the period that the servo rewinds the turnlimit potentiometer.

FIGURE 3 shows a magnetic clutch and brake assembly designed to be usedwith a pen indexing device. This assembly enables the transcribingelement to be more accurately positioned by preventing jitter,servo-hunt, backlash, etc. The errors introduced by servo-hunt, jitter,backlash, etc., are prevented by the automatic operation of the clutchand the brake during the positioning and transcribing operations, aswill be detailed hereinafter. In addition, when the clutch-brakeassembly is used with a servo-driven indexing device, it introduces moreaccuracy into the over-all system than is otherwise possible. It is wellknown to one skilled in the art that a servo system can be designed tolinearly position an item within an accuracy of approximately one-halfpercent. Consequently, if the pen indexing device is operated over adistance of, say, four to five feet, the length of a conventionalseismic oflice computer drum, the one-half percent error in locating thepen is significant. However, if the device is operated through a seriesof short steps by the use of a turn limit potentiometer, or the like, asdescribed in the band-pulley paragraph, the error is only the sum ofonehalf percent of each of the short distances traveled. This amounts toa considerable decrease in the over-all error.

Regardless of the type of pen indexing system utilized, the clutch isused to engage a motion imparting means, be it band, rod, screw, etc.,and the brake, if utilized, is used to engage a stationary means. 1

The magnetic brake-clutch assembly, FIGURE 3, as used in FIGURES 2 and4, can include two modified relays mounted on a pen housing, or thelike, and electrically connected through a microswitch or othercontrolling means. If relays are used as clutch 225 and brake 227,

Clutch 225 includes solenoid 229, core 231, spring-loaded rocker arm 233and stop 235. Brake 227 includes solenoid 237, core 239, spring-loadedrocker arm 241 and stop 243. The clutch is designed so that rocker arm233 rides over a motion imparting means and the brake is designed sothat rocker arm 241 rides over a stationary means. The operation of theclutch-brake assembly is simple and effective in operation. When the penhousing 209 is being positioned by the motion imparting means, theclutchs rocker arm is firmly clamped against the means by the activationof solenoid 229. The brakes rocker arm allows the stationary means to bepassed freely under it since its solenoid is not activated. When the penhousing has been indexed a preselected distance, depending on the typeof system used, the clutch is de-activated and, if desired, the brake isactivated. The de-activation of the clutch prevents the driving meansfrom moving the housing until the clutch is re-activated. The brake mayor may not be required depending on the type of index system used. If adevice, such as shown in FIGURE 2, is used, the brake should at leastbeactivated during the time the turn limit potentiometer is rewound;however, if a screw drive modification of FIGURE 2, as discussed in thesame subheading, is used, a brake is not necessary. If'a device such asshown in FIGURE4 is utilized, a brake should be used and applied atleast during the times the plunger is returning to its de-activatedposition.

they are modified so the relay contacts are not utilized.

Linear motion solenoid pen indexing device FIGURE 4 shows an isometricdrawing, partially in section, of a linear motion solenoid pen indexingdevice in which the incremental motion is incorporated to insureaccuracy in positoining the pen housing. The motion imparting means isthe ultimate in simplicity of operation and construction and yetmaintains a high degree of accuracy. The device consists of aconventional solenoid 257 mounted in housing 259 positioned within frame261 by set screw 263. Solenoid plunger 265 is slidably positioned insidesolenoid 257 and connected to band 267 which in turn is connectedthrough spring 269 to frame 271. Frame element 273 preventsspring-loaded band 267 from pulling the plunger from its position insidethe solenoid. Set screw 263 determines the travel distance or the gapbetween the plunger and the housing. Second band 275 is connectedbetween frames 271 and 261. Pen

housing 269 mounting magnetic clutch 225 and magnetic brake 227 andtraveling on ways 285 and 207 can be the same as shown in FIGURE 2. Thisdevice can receive its command voltage and magnetic brake-clutchvoltages directly from the switching matrix pulse circuit, such as shownin FIGURE 1. Therefore, when this type of index is used, control circuit3, FIGURE 1, is simplified considerably. Set screw 263, FIGURE 4, isutilized to adjust plunger travel distance and, therefore, the intervalbetween transcribing channels on drum 17, FIGURE 1. A stepping switch,not shown, can be used in conjunction with the pulse circuit to step thepen housing to the desired position without the use of the pulsecircuit. In addition, the pen housing can be manually freewheeled to thedesired position by the use of microswitch 245.

In operation, previously described brake-clutch signal voltagesde-activate the brake and activate the clutch. Simultaneously, a commandvoltage reaches solenoid 257 and a magnetic field is set up in adirection to pull the plunger into the solenoid until it strikes housing259. The amount of plunger travel and linear motion applied to band 267is determined by the setting of screw 263. Since the clutch now gripsband 267 and brake 227 does not grip band 275, the linear movementapplied to band 267 also moves the pen housing. After the movement ofthe plunger is stopped by housing 202, the clutch is deactivated and thebrake is activated by reversing the signals from the relay controlcircuit. When the command voltage is terminated, solenoid 257 isde-energized, allowing spring 269 to pull the band and plunger to theiroriginal position. However, the pen carriage does not follow the bandmovement rearward since the brake is now holding the pen housing tofixed band 275 and the clutch allows its band to move under its rockerarm. This stepping procedure is repeated during the transcribing cycleuntil all the selected magnetic channels have been reproduced. Whenpatch plugs 35, 37, and 39, FIGURE 1, in the playback switching matrixare arranged so that one or more channels are omitted, solenoid 257,FIGURE 4, receives an appropriate number of pulses to move the penhousing over the omitted channels.

The indexing system can be made bidirectional by reversing the functionsof the clutch and brake. When the functions are reversed, the pen movesunder the inways supported by said (d) at least one pen carried by saidpen housing,

(e) gear means fixed to one end of said frame member,

(f) an anchor support rigidly attached to said first tubular way nearthe end of said frame member remote to said gear means,

(g) a first pulley associated with and attached to said gear means,

(h) a second pulley mounted on the end of said frame member remote tosaid gear means,

(i) a continuous band mounted on said first and second pulleys so that aportion thereof passes through said first tubular way,

(j) a connecting band joining said gear means and said anchor support,

(k) a magnetic clutch mounted on said pen housing and adapted to engagesaid continuous band, and

(l) a magnetic brake mounted on said pen housing which is adapted toengage said connecting band. 2. In a device as set forth in claim 1,wherein a turn limit potentiometer is associated with and attached tosaid gear means.

3. In a device as set forth in claim 2, wherein a servo motor operatessaid gear means.

4. A linear motion, solenoid pen indexing device, comprising,

(a) a frame member having opposed terminal portions, (b) at least twotraveling ways connecting said terminal portions, (0) a pen housingslidably mounted on said traveling ways, ((1) at least one pen carriedby said pen housing,

(e) a movable housing slidably mounted on one terminal portion of saidframe member,

(f) a solenoid including a plunger and a coil adapted to fit within saidmovable housing,

(g) positioning means for locating said movable housing relative to saidframe member,

(h) spring means connected to the terminal portion of the frame memberopposed to said movable housing,

(i) a first band connected to the plunger of said solenoid and to saidspring means,

(j) stop means to keep said plunger within its position within saidsolenoid,

(k) a second band connected between the terminal portions of the framemember,

(l) a magnetic clutch mounted on said pen housing and adapted to engagesaid first band, and

(m) a magnetic brake mounted on said pen housing and which is adapted toengage said second band.

References Cited by the Examiner UNITED STATES PATENTS 1,163,280 12/1915Stevens 346-33 X 2,387,563 10/1945 Schapple 34649 2,626,979 1/1953 Woods346-139 X 2,847,859 8/1958 Lynott 7437 2,926,984 3/1960 Gerbrands 346139RICHARD B. WILKINSON, Primary Examiner.

I. HARTARY, Assistant Examiner.

1. A BAND PULLEY PEN INDEXING DEVICE, COMPRISING, (A) A FRAME MEMBER,(B) FIRST AND SECOND TUBULAR WAYS SUPPORTED BY SAID FRAME MEMBER, (C) APEN HOUSING SLIDABLY MOUNTED ON SAID TUBULAR WAYS, (D) AT LEAST ONE PENCARRIED BY SAID PEN HOUSING, (E) GEAR MEANS FIXED TO ONE END OF SAIDFRAME MEMBER, (F) AN ANCHOR SUPPORT RIGIDLY ATTACHED TO SAID FIRSTTUBULAR WAY NEAR THE END OF SAID FRAME MEMBER REMOTE TO SAID GEAR MEANS,(G) A FIRST PULLEY ASSOCIATED WITH AND ATTACHED TO SAID GEAR MEANS, (H)A SECOND PULLEY MOUNTED ON THE END OF SAID FRAME MEMBER REMOTE TO SAIDGEAR MEANS, (I) A CONTINUOUS BAND MOUNTED ON SAID FIRST AND SECONDPULLEYS SO THAT A PORTION THEREOF PASSES THROUGH SAID FIRST TUBULAR WAY,(J) A CONNECTING BAND JOINING SAID GEAR MEANS AND SAID ANCHOR SUPPORT,(K) A MAGNETIC CLUTCH MOUNTED ON SAID PEN HOUSING AND ADAPTED TO ENGAGESAID CONTINUOUS BAND, AND (L) A MAGNETIC BRAKE MOUNTED ON SAID PENHOUSING WHICH IS ADAPTED TO ENGAGE SAID CONNECTING BAND.